Is the decaffeination process bad for your health?by Jennifer Bowden
Decaffeinated coffee and tea are rising in popularity, but not all drinks are created equal.
Caffeine is a natural compound found in the leaves, seeds or fruits of many plants, including coffee, tea and cocoa. The stimulant effect of caffeine offers a welcome pick-me-up in the morning, but those same effects are less welcome later in the day when it can disrupt sleep.
Decaffeinated coffee and tea are a fantastic solution for the avid coffee drinker or tea lover who also likes their beauty sleep. By removing much of the caffeine from green coffee beans before roasting, or from tea leaves, manufacturers are able to offer a relatively low-caffeine drink.
One of three methods is typically used to remove caffeine: using solvents in a direct or indirect process, the Swiss water process or the carbon dioxide process.
Decaffeination can be achieved efficiently using solvents such as dichloromethane or ethyl acetate. The coffee beans or tea leaves are soaked either directly or indirectly in the solvent, removing the caffeine and leaving most of the important flavour and health-giving compounds.
However, dichloromethane is classified as a probable human carcinogen by the International Agency for Research on Cancer. Although the residue levels of dichloromethane remaining on decaffeinated coffee and tea have been found to fall within safe levels, this solvent method of decaffeination remains highly unpopular with many consumers – perhaps not surprisingly.
When ethyl acetate is used as the solvent, the process may be referred to as “naturally decaffeinated” because the chemical is naturally found in tea. Processing with ethyl acetate may be a less desirable option, though, as it is reportedly difficult for manufacturers to remove it completely after the decaffeination process, and some consumers describe teas decaffeinated this way as having a “chemical taste”.
Water-processed decaffeination is a far more consumer-friendly method as it involves soaking coffee beans in water to remove the caffeine in a multi-step process that ensures most of the flavour compounds are retained. More often used for coffee than tea, it may lead to greater losses of flavour compounds than the solvent process.
The carbon dioxide process is more popular for decaffeinating tea, which is soaked in supercritical carbon dioxide rather than water. Supercritical carbon dioxide is a fluid-like state of the gas, created by increasing the temperature and pressure. Caffeine seeps out of the leaves into the supercritical carbon dioxide, which is then filtered out. The carbon dioxide is ultimately recycled and reused. When carefully managed, the carbon dioxide process retains flavour and health-giving compounds such as the all-important antioxidants found in green and black teas.
The question is, what decaffeination process is being used by the manufacturer of your tea or coffee? They’re unlikely to advertise it on the product but a quick search of their website or a call to their customer help desk should provide an answer.
I checked a few products while writing this column and discovered that Dilmah uses the carbon dioxide process to decaffeinate its teas; Nescafé uses the water process and Moccona uses dichloromethane on its coffees.
If you prefer not to consume products that have been decaffeinated using solvents such as dichloromethane, there are teas and coffees decaffeinated using water or carbon dioxide, or naturally caffeine-free drinks such as rooibos or herbal teas.
This article was first published in the August 18, 2018 issue of the New Zealand Listener.
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